Nutrients

Question 1

Which macromolecules can plants build using only water and CO2?

Answer 1

Carbohydrates and lipids

Question 2

Why do plants need nutrients if they can build quite a lot out of just CO2 and water?

Answer 2

Anything in the plant that actually does something needs atoms other than just carbon, hydrogen, and oxygen

Question 3

What elements make up chlorophyll?

Answer 3

Carbon, hydrogen, oxygen, nitrogen, magnesium

Question 4

What is an essential element?

Answer 4

Any atom that is required for a plant to complete its life cycle

Question 5

Is an element that is only required for reproduction still an essential element?

Answer 5

Yes

Question 6

How do we test if one particular nutrient is essential for a plant?

Answer 6

Hydroponics

Question 7

Why is growing plants in water problematic? How do we get around that with hydroponics?

Answer 7

Anything water saturated is anaerobic, and the roots need oxygen. Hydroponics pumps air into the water to supply the roots with oxygen

Question 8

In a hydroponics experiment that tests if a particular nutrient is essential, what would the control be?

Answer 8

Plant grown in a complete nutrient solution

Question 9

Does every single plant need the same nutrients in the same amounts?

Answer 9

No, lots of variation between plants

Question 10

How are the vast majority of nutrients transported in the plant?

Answer 10

Dissolved in water and drawn up with it in the xylem

Question 11

How do plants in humid environments like cloud forests keep drawing up nutrients?

Answer 11

They actively transport water out of their leaves to keep the tension in the xylem to keep bringing up nutrients

Question 12

Which 9 elements are always required in large quantities?

Answer 12

1. Carbon
2. Oxygen
3. Hydrogen
4. Nitrogen
5. Phosphorus
6. Calcium
7. Potassium
8. Sulfur
9. Magnesium

Question 13

What are macronutrients? How much of the plant do they make up?

Answer 13

Nutrients needed in large amounts. They make up 96% of the plant biomass, with 95% of that being just C, H, and O

Question 14

What are micronutrients?

Answer 14

Nutrients only required in small amounts

Question 15

Why are micronutrients required in small amounts? What do they do in plants?

Answer 15

They are often toxic in high amounts. Often are involved in enzyme function

Question 16

What does an iron deficiency look like in a plant?

Answer 16

Chlorosis and yellowing from the inside out

Question 17

What does a magnesium deficiency look like in a plant?

Answer 17

Mottled chlorosis and leaf deformation, necrosis on the tips of the leaves

Question 18

What does a nitrogen deficiency look like in a plant?

Answer 18

Leaves turn completely yellow and the lower leaves get sacrificed first

Question 19

What does a sulfur deficiency look like in a plant?

Answer 19

Leaves are entirely yellow or mottled and the upper leaves get sacrificed first

Question 20

What does a phosphorous deficiency look like in a plant?

Answer 20

Leaves are deformed towards the top of the plant, but all the leaves stay green because chlorophyll is unaffected

Question 21

What does a potassium deficiency look like in a plant?

Answer 21

Necrosis around the edges

Question 22

What does a calcium deficiency look like in a plant?

Answer 22

Odd necrosis patterns

Question 23

Which other nutrient deficiency does a nitrogen deficiency look a lot alike to? How do you tell them apart?

Answer 23

Looks a lot like a sulfur deficiency. Nitrogen deficient plants lose their lower leaves first, and sulfur deficient plants lose their upper leaves first

Question 24

What determines nutrient availability in the soil? Why?

Answer 24

If there are charged particles in the soil. They will attract ions of the opposite charge and immobilize them

Question 25

What determines how much nutrients are available to plants?

Answer 25

pH and charged particles in the soil

Question 26

Is nutrient uptake by plants active or passive transport?

Answer 26

Mostly active transport for better control, but some are passive transport

Question 27

What is leaf senescence?

Answer 27

The final stage of leaf development which involves the reuptake of nutrients in the leaves by the plant

Question 28

Why is leaf senescence critical to plant’s fitness?

Answer 28

Nutrients are hard to come by, and the plant would lose a ton of nutrients if the leaves fell off before the nutrients were reabsorbed. Also molecules like chlorophyll are expensive to make

Question 29

What is nutrient salvage?

Answer 29

Hydrolysis of macromolecules followed by remobilization towards the roots

Question 30

Which hormones regulate the onset of leaf senescence?

Answer 30

Ethylene and ABA

Question 31

What signals the beginning of leaf senescence?

Answer 31

External stimuli like light and temperature, which determines the balance of hormones

Question 32

What tissue in the leaves is the last to be broken down?

Answer 32

The vascular tissue, especially the phloem. It needs to be intact to transport the nutrients into the roots

Question 33

What is the final stage of leaf senescence? What triggers it?

Answer 33

Leaf abscission. Triggered by ethylene and ABA